Search

This review describes the dynamic phenomena in the atmosphere of Mars that are visible in images taken in the visual range through cloud formation and dust lifting. We describe the properties of atmospheric features traced by aerosols covering a large range of spatial and temporal scales, including dynamical interpretations and modelling when available. We present the areographic distribution and the daily and seasonal cycles of those atmospheric phenomena. We rely primarily on images taken by cameras on Mars Express.

The Mars Environmental Dynamics Analyzer instrument, on board NASA's Mars 2020 Perseverance rover, includes a number of sensors to characterize the Martian atmosphere. One of these sensors is the Radiation and Dust Sensor (RDS) that measures the solar irradiance at different wavelengths and geometries. We analyzed the RDS observations made during twilight for the period between sol 71 and 492 of the mission (Ls 39°–262°, Mars Year 36) to characterize the clouds over the Perseverance rover site. Using the ratio between the irradiance at zenith at 450 and 750 nm, we inferred that the main constituent of the detected high-altitude aerosol layers was ice from Ls = 39°–150° (cloudy period), and dust from Ls 150°–262°. A total of 161 twilights were analyzed in the cloudy period using a radiative transfer code and we found: (a) signatures of clouds/hazes in the signals in 58% of the twilights; (b) most of the clouds had altitudes between 40 and 50 km, suggesting water ice composition, and had particle sizes between 0.6 and 2 µm; (c) the cloud activity at sunrise is slightly higher that at sunset, likely due to the differences in temperature; (d) the time period with more cloud detections and with the greatest cloud opacities is during Ls 120°–150°; and (e) a notable decrease in the cloud activity around aphelion, along with lower cloud altitudes and opacities. This decrease in cloud activity indicates lower concentrations of water vapor or cloud condensation nuclei (dust) around this period in the Martian mesosphere.

Mars 2020 Mars Environmental Dynamics Analyzer (MEDA) instrument data acquired during half of a Martian year (Ls 13°–180°), and modeling efforts with the Mars Regional Atmospheric Modeling System (MRAMS) and the Mars Climate Database (MCD) enable the study of the seasonal evolution and variability of nocturnal atmospheric turbulence at Jezero crater. Nighttime conditions in Mars's Planetary Boundary Layer are highly stable because of strong radiative cooling that efficiently inhibits convection. However, MEDA nighttime observations of simultaneous rapid fluctuations in horizontal wind speed and air temperatures suggest the development of nighttime turbulence in Jezero crater. Mesoscale modeling with MRAMS also shows a similar pattern and enables us to investigate the origins of this turbulence and the mechanisms at play. As opposed to Gale crater, less evidence of turbulence from breaking mountain wave activity was found in Jezero during the period studied with MRAMS. On the contrary, the model suggests that nighttime turbulence at Jezero crater is explained by increasingly strong wind shear produced by the development of an atmospheric bore-like disturbance at the nocturnal inversion interface. These atmospheric bores are produced by downslope winds from the west rim undercutting a strong low-level jet aloft from ∼19:00 to 01:00 LTST and from ∼01:00 LTST to dawn when undercutting weak winds aloft. The enhanced wind shear leads to a reduction in the Richardson number and an onset of mechanical turbulence. Once the critical Richardson Number is reached (Ri ∼ <0.25), shear instabilities can mix warmer air aloft down to the surface.

The atmosphere of Jupiter has east–west zonal jets that alternate as a function of latitude as tracked by cloud motions at tropospheric levels. Above and below the cold tropopause at ~100 mbar, the equatorial atmosphere is covered by hazes at levels where thermal infrared observations used to characterize the dynamics of the stratosphere lose part of their sensitivity. James Webb Space Telescope observations of Jupiter in July 2022 show these hazes in higher detail than ever before and reveal the presence of an intense (140 m s−1) equatorial jet at 100–200 mbar (70 m s−1 faster than the zonal winds at the cloud level) that is confined to ±3° of the equator and is located below stratospheric thermal oscillations that extend at least from 0.1 to 40 mbar and repeat in multiyear cycles. This suggests that the new jet is a deep part of Jupiter’s Equatorial Stratospheric Oscillation and may therefore vary in strength over time.

The pressure sensors on Mars rover Perseverance measure the pressure field in the Jezero crater on regular hourly basis starting in sol 15 after landing. The present study extends up to sol 460 encompassing the range of solar longitudes from Ls ∼ 13°–241° (Martian Year (MY) 36). The data show the changing daily pressure cycle, the sol-to-sol seasonal evolution of the mean pressure field driven by the CO2 sublimation and deposition cycle at the poles, the characterization of up to six components of the atmospheric tides and their relationship to dust content in the atmosphere. They also show the presence of wave disturbances with periods 2–5 sols, exploring their baroclinic nature, short period oscillations (mainly at night-time) in the range 8–24 min that we interpret as internal gravity waves, transient pressure drops with duration ∼1–150 s produced by vortices, and rapid turbulent fluctuations. We also analyze the effects on pressure measurements produced by a regional dust storm over Jezero at Ls ∼ 155°.

The Mars Environmental Dynamics Analyzer instrument on Mars 2020 has five Atmospheric Temperature Sensors at two altitudes (0.84 and 1.45 m) plus a Thermal InfraRed Sensor that measures temperatures on the surface and at ∼40 m. We analyze the measurements from these sensors to describe the evolution of temperatures in Jezero up to mission sol 400 (solar longitude LS = 13°–203°). The diurnal thermal cycle is characterized by a daytime convective period and a nocturnal stable atmosphere with a variable thermal inversion. We find a linear relationship between the daytime temperature fluctuations and the vertical thermal gradient with temperature fluctuations that peak at noon with typical values of 2.5 K at 1.45 m. In the late afternoon (∼17:00 Local True Solar Time), the atmosphere becomes vertically isothermal with vanishing fluctuations. We observe very small seasonal changes in air temperatures during the period analyzed. This is related to small changes in solar irradiation and dust opacity. However, we find significant changes in surface temperatures that are related to the variety of thermal inertias of the terrains explored along the traverse of Perseverance. These changes strongly influence the vertical thermal gradient, breaking the nighttime thermal inversion over terrains of high thermal inertia. We explore possible detections of atmospheric tides on near-surface temperatures and we examine variations in temperatures over timescales of a few sols that could be indicative of atmospheric waves affecting near-surface temperatures. We also discuss temperatures during a regional dust storm at LS = 153°–156° that simultaneously warmed the near surface atmosphere while cooling the surface.

Context. First identified in 2016 by the Japan Aerospace eXploration Agency (JAXA) Akatsuki mission, the discontinuity or disruption is a recurrent wave observed to propagate over decades at the deeper clouds of Venus (47–56 km above the surface), while its absence at the top of the clouds (∼70 km) suggests that it dissipates at the upper clouds and contributes to the maintenance of the puzzling atmospheric superrotation of Venus through wave-mean flow interaction. Aims. Taking advantage of the campaign of ground-based observations undertaken in coordination with the Akatsuki mission from December 2021 until July 2022, we undertook the longest uninterrupted monitoring of the cloud discontinuity to date to obtain a pioneering long-term characterisation of its main properties and to better constrain its recurrence and lifetime. Methods. The dayside upper, middle, and nightside lower clouds were studied with images acquired by the Akatsuki Ultraviolet Imager (UVI), amateur observers, and SpeX at the NASA Infrared Telescope Facility (IRTF). Hundreds of images were inspected in search of the discontinuity events and to measure key properties such as its dimensions, orientation, and rotation period. Results. We succeeded in tracking the discontinuity at the middle clouds during 109 days without interruption. The discontinuity exhibited properties nearly identical to measurements in 2016 and 2020, with an orientation of 91° ±8°, length of 4100 ± 800 km, width of 500 ± 100 km, and a rotation period of 5.11 ± 0.09 days. Ultraviolet images during 13–14 June 2022 suggest that the discontinuity may have manifested at the top of the clouds during ∼21 h as a result of an altitude change in the critical level for this wave, due to slower zonal winds.

En este trabajo se identifican y estudian las tormentas de polvo que se produjeron en el hemisferio norte del planeta Marte durante los primeros meses de estudio del rover Perseverance. Para la identificación de las tormentas se han empleado las imágenes del Visual Monitoring Camera (VMC) a bordo del Mars Express (MEX) y del Mars Color Imager (MARCI) a bordo del Mars Recoinnaissance Orbiter (MRO). El objetivo principal de este trabajo es la búsqueda en las imágenes obtenidas por estas cámaras de las inestabilidades producidas en el hemisferio norte del planeta desde la llegada del rover Perseverance (18 de febrero de 2021) hasta el 31 de agosto del mismo año (Ls = 5.4° − 92.8° del año 36 en Marte). En las imágenes estudiadas se han identificado numerosas tormentas de polvo de todo tipo: nubes compactas, espirales de polvo, arcos abiertos, etc. Estos fenómenos atmosféricos observados se mueven hacia el este evolucionando de manera rápida y diaria. Además de identificar y medir estas estructuras, se ha realizado un análisis teórico para entender las inestabilidades que causan estos fenómenos meteorológicos. Castellano

NASA's Perseverance rover's Mars Environmental Dynamics Analyzer is collecting data at Jezero crater, characterizing the physical processes in the lowest layer of the Martian atmosphere. Here we present measurements from the instrument's first 250 sols of operation, revealing a spatially and temporally variable meteorology at Jezero. We find that temperature measurements at four heights capture the response of the atmospheric surface layer to multiple phenomena. We observe the transition from a stable night-time thermal inversion to a daytime, highly turbulent convective regime, with large vertical thermal gradients. Measurement of multiple daily optical depths suggests aerosol concentrations are higher in the morning than in the afternoon. Measured wind patterns are driven mainly by local topography, with a small contribution from regional winds. Daily and seasonal variability of relative humidity shows a complex hydrologic cycle. These observations suggest that changes in some local surface properties, such as surface albedo and thermal inertia, play an influential role. On a larger scale, surface pressure measurements show typical signatures of gravity waves and baroclinic eddies in a part of the seasonal cycle previously characterized as low wave activity. These observations, both combined and simultaneous, unveil the diversity of processes driving change on today's Martian surface at Jezero crater.

180 p., Esta Tesis se centra en el estudio de la Gran Mancha Roja de Júpiter (GRS, por sus siglas en inglés), su entorno y el Óvalo BA. En primer lugar, se analizan desde el punto de vista dinámico las interacciones que la GRS experimentó con una serie de vórtices en 2019. Mediante este análisis, se identifican las zonas de interés para su estudio mediante modelización de transporte radiativo. Se estudiaron un total de 13 regiones para el período de tiempo comprendido entre 2015 y 2021 empleando imágenes de la cámara WFC3 del Telescopio Espacial Hubble. En concreto, se analizan las propiedades de las nieblas y nubes para niveles de presión inferiores a 1 bar. Entre otras conclusiones, encontramos un colorante compatible con el agente más prometedor en la literatura. En cuanto al Óvalo BA, el cambio de color rojizo a blanquecino entre 2018 y 2019 es explicado por nuestro modelo con una reducción en la concentración de dicho agente colorante en el óvalo. Finalmente, se presenta una exploración de las condiciones microfísicas para la generación de aerosoles en la GRS, incluyendo el desarrollo de un código unidimensional que trata el transporte vertical de partículas.

The Radiation and Dust Sensor is one of six sensors of the Mars Environmental Dynamics Analyzer onboard the Perseverance rover from the Mars 2020 NASA mission. Its primary goal is to characterize the airbone dust in the Mars atmosphere, inferring its concentration, shape and optical properties. Thanks to its geometry, the sensor will be capable of studying dust-lifting processes with a high temporal resolution and high spatial coverage. Thanks to its multiwavelength design, it will characterize the solar spectrum from Mars’ surface. The present work describes the sensor design from the scientific and technical requirements, the qualification processes to demonstrate its endurance on Mars’ surface, the calibration activities to demonstrate its performance, and its validation campaign in a representative Mars analog. As a result of this process, we obtained a very compact sensor, fully digital, with a mass below 1 kg and exceptional power consumption and data budget features.

Context. A stellar occultation by Neptune's main satellite, Triton, was observed on 5 October 2017 from Europe, North Africa, and the USA. We derived 90 light curves from this event, 42 of which yielded a central flash detection. Aims. We aimed at constraining Triton's atmospheric structure and the seasonal variations of its atmospheric pressure since the Voyager 2 epoch (1989). We also derived the shape of the lower atmosphere from central flash analysis. Methods. We used Abel inversions and direct ray-tracing code to provide the density, pressure, and temperature profiles in the altitude range similar to 8 km to similar to 190 km, corresponding to pressure levels from 9 mu bar down to a few nanobars. Results. (i) A pressure of 1.18 +/- 0.03 mu bar is found at a reference radius of 1400 km (47 km altitude). (ii) A new analysis of the Voyager 2 radio science occultation shows that this is consistent with an extrapolation of pressure down to the surface pressure obtained in 1989. (iii) A survey of occultations obtained between 1989 and 2017 suggests that an enhancement in surface pressure as reported during the 1990s might be real, but debatable, due to very few high S/N light curves and data accessible for reanalysis. The volatile transport model analysed supports a moderate increase in surface pressure, with a maximum value around 2005-2015 no higher than 23 mu bar. The pressures observed in 1995-1997 and 2017 appear mutually inconsistent with the volatile transport model presented here. (iv) The central flash structure does not show evidence of an atmospheric distortion. We find an upper limit of 0.0011 for the apparent oblateness of the atmosphere near the 8 km altitude.

On May 31, 2020 a short-lived convective storm appeared in one of the small cyclones of Jupiter's South Temperate Belt (STB) at planetographic latitude 30.8S. The outbreak was captured by amateur astronomer Clyde Foster in methane-band images, became widely known as Clyde's Spot, and was imaged at very high resolution by the Junocam instrument on board the Juno mission 2.5 days later. Junocam images showed a white two-lobed cyclonic system with high clouds observed in the methane-band at 890 nm. The storm evolved over a few days to become a dark feature that showed turbulence for months, presented oscillations in its drift rate, and slowly expanded, first into a Folded Filamentary Region (FFR), and later into a turbulent segment of the STB over a timescale of one year. On August 7, 2021, a new storm strikingly similar to Clyde's Spot erupted in a cyclone of the STB. The new storm exhibited first a similar transformation into a turbulent dark feature, and later transformed into a dark cyclone fully formed by January 2022. We compare the evolution into a FFR of Clyde's Spot with the formation of a FFR observed by Voyager 2 in 1979 in the South South Temperate Belt (SSTB) after a convective outburst in a cyclone that also developed a two-lobed shape. We also discuss the contemporaneous evolution of an additional cyclone of the STB, which was similar to the one were Clyde's Spot developed. This cyclone did not exhibit visible internal convective activity, and transformed from pale white in 2019, with low contrast with the environment, to dark red in 2020, and thus, was very similar to the outcome of the second storm. This cyclone became bright again in 2021 after interacting with Oval BA. We present observations of these phenomena obtained by amateur astronomers, ground-based telescopes, Hubble Space Telescope and Junocam. This study reveals that short-lived small storms that are active for only a few days can produce complex longterm changes that extend over much large

Wind speeds measured by the Mars 2020 Perseverance rover in Jezero crater were fitted as a Weibull distribution. InSight wind data acquired in Elysium Planitia were also used to contextualize observations. Jezero winds were found to be much calmer on average than in previous landing sites, despite the intense aeolian activity observed. However, a great influence of turbulence and wave activity was observed in the wind speed variations, thus driving the probability of reaching the highest wind speeds at Jezero, instead of sustained winds driven by local, regional, or large-scale circulation. The power spectral density of wind speed fluctuations follows a power-law, whose slope deviates depending on the time of day from that predicted considering homogeneous and isotropic turbulence. Daytime wave activity is related to convection cells and smaller eddies in the boundary layer, advected over the crater. The signature of convection cells was also found during dust storm conditions, when prevailing winds were consistent with a tidal drive. Nighttime fluctuations were also intense, suggesting strong mechanical turbulence. Convective vortices were usually involved in rapid wind fluctuations and extreme winds, with variations peaking at 9.2 times the background winds. Transient high wind events by vortex-passages, turbulence, and wave activity could be driving aeolian activity at Jezero. We report the detection of a strong dust cloud of 0.75–1.5 km in length passing over the rover. The observed aeolian activity had major implications for instrumentation, with the wind sensor suffering damage throughout the mission, probably due to flying debris advected by winds.

We performed a unique Venus observation campaign to measure the disk brightness of Venus over a broad range of wavelengths in 2020 August and September. The primary goal of the campaign was to investigate the absorption properties of the unknown absorber in the clouds. The secondary goal was to extract a disk mean SO2 gas abundance, whose absorption spectral feature is entangled with that of the unknown absorber at ultraviolet wavelengths. A total of three spacecraft and six ground-based telescopes participated in this campaign, covering the 52–1700 nm wavelength range. After careful evaluation of the observational data, we focused on the data sets acquired by four facilities. We accomplished our primary goal by analyzing the reflectivity spectrum of the Venus disk over the 283–800 nm wavelengths. Considerable absorption is present in the 350–450 nm range, for which we retrieved the corresponding optical depth of the unknown absorber. The result shows the consistent wavelength dependence of the relative optical depth with that at low latitudes, during the Venus flyby by MESSENGER in 2007, which was expected because the overall disk reflectivity is dominated by low latitudes. Last, we summarize the experience that we obtained during this first campaign, which should enable us to accomplish our second goal in future campaigns.

175 p., En esta tesis se estudian varios fenómenos meteorológicos que tienen lugar en la atmósfera de Marte con imágenes de la cámara VMC de Mars Express. Otros instrumentos que vuelan en misiones en órbita de Marte se utilizan como soporte. Como parte de la tesis, se han desarrollado nuevas metodologías de trabajo que han implicado la operación de VMC, su calibrado, y la preparación de pipelines de procesado de datos.Los fenómenos meteorológicos que se estudian en esta tesis son tres: 1. Las nubes crepusculares noctilucentes en Marte. 2. La nube elongada de Arsia Mons (AMEC). 3. La gran tormenta global de Marte de 2018 en su penetración hacia la región polar sur.Como parte de la tesis se ha desarrollado el primer estudio sistemático de nubes noctilucentes en Marte, determinando por primera vez su distribución geográfica y temporal. También se ha descrito por primera vez en la literatura científica la AMEC, un fenómeno meteorológico extraordinario para el que también se ha dado un principio de explicación con la ayuda de un modelo numérico de mesoescala. El estudio de esta nube de origen orográfico ha llevado a conclusiones novedosas sobre la formación de nubes orográficas en Marte. Por último, el estudio de la gran tormenta de 2018 muestra vientos del vórtice polar sur que no son enteramente coincidentes con los predichos por los modelos de circulación general.

Dust devils (convective vortices loaded with dust) are common at the surface of Mars, particularly at Jezero crater, the landing site of the Perseverance rover. They are indicators of atmospheric turbulence and are an important lifting mechanism for the Martian dust cycle. Improving our understanding of dust lifting and atmospheric transport is key for accurate simulation of the dust cycle and for the prediction of dust storms, in addition to being important for future space exploration as grain impacts are implicated in the degradation of hardware on the surface of Mars. Here we describe the sound of a Martian dust devil as recorded by the SuperCam instrument on the Perseverance rover. The dust devil encounter was also simultaneously imaged by the Perseverance rover's Navigation Camera and observed by several sensors in the Mars Environmental Dynamics Analyzer instrument. Combining these unique multi-sensorial data with modelling, we show that the dust devil was around 25m large, at least 118m tall, and passed directly over the rover travelling at approximately 5ms-1. Acoustic signals of grain impacts recorded during the vortex encounter provide quantitative information about the number density of particles in the vortex. The sound of a Martian dust devil was inaccessible until SuperCam microphone recordings. This chance dust devil encounter demonstrates the potential of acoustic data for resolving the rapid wind structure of the Martian atmosphere and for directly quantifying wind-blown grain fluxes on Mars.

In a previous work (Hernandez-Bernal et al., 2021, ) we performed an observational analysis of the Arsia Mons Elongated Cloud (AMEC), which stands out due to its impressive size and shape, quick dynamics, and the fact that it happens during the Martian dusty season. Observations show that its morphology can be split in a head, on the western slope of the volcano of around 120 km in diameter; and a tail, that expands to the west reaching more than 1,000 km in length, making the AMEC the longest orographic cloud observed so far in the solar system. In this work we run the Laboratoire de Meteorologie Dynamique Mesoscale Model to gain insight into the physics of the AMEC. We note that it is coincident in terms of local time and seasonality with the fastest winds on the summit of Arsia Mons. A downslope windstorm on the western slope is followed by a hydraulic-like jump triggering a strong vertical updraft that propagates upwards in the atmosphere, causing a drop in temperatures of down to 30 K at 40-50 km in altitude, spatially and temporarily coincident with the observed head of the AMEC. However the model does not reproduce the microphysics of this cloud: the optical depth is too low and the expansion of the tail does not happen in the model. The observed diurnal cycle is correctly captured by the model for the head of the cloud. This work raises new questions that will guide future observations of the AMEC.

Despite the importance of sand and dust to Mars geomorphology, weather, and exploration, the processes that move sand and that raise dust to maintain Mars' ubiquitous dust haze and to produce dust storms have not been well quantified in situ, with missions lacking either the necessary sensors or a sufficiently active aeolian environment. Perseverance rover's novel environmental sensors and Jezero crater's dusty environment remedy this. In Perseverance's first 216 sols, four convective vortices raised dust locally, while, on average, four passed the rover daily, over 25% of which were significantly dusty ("dust devils"). More rarely, dust lifting by nonvortex wind gusts was produced by daytime convection cells advected over the crater by strong regional daytime upslope winds, which also control aeolian surface features. One such event covered 10 times more area than the largest dust devil, suggesting that dust devils and wind gusts could raise equal amounts of dust under nonstorm conditions.

On May 31, 2020 a convective storm appeared in one small cyclone in the South Temperate Belt (STB) of Jupiter. The storm, nicknamed as Clyde's Spot, had an explosive start and quickly diminished in activity in a few days. However, it left a highly turbulent cyclone as a remnant that evolved to become a turbulent segment of the STB in a time-scale of one year. A very similar storm erupted on August 7, 2021 in another cyclone of the STB with a similar initial phenomenology. In both cases, the outbreaks started in cyclones that were the result of the merger of pre-existing vortices. In a previous paper we presented an observational study of these storms compared with a similar cyclonic convective system observed during the Voyager 2 flyby [Hueso et al., Convective storms in closed cyclones in Jupiter's South Temperate Belt: (I) Observations, Icarus, 380, 2022]. Here we present numerical simulations of these vortices and storms with the Explicit Planetary Isentropic-Coordinate (EPIC) numerical model. We simulate mergers of cyclones in Jupiter's STB and investigate the deep structure of the resulting cyclone and its capability to uplift material from the water condensation level. Convection is introduced in the model imposing heating sources whose vertical extent, horizontal size and duration are free parameters that we explore. Our simulations reproduce the cloud field of both storms after short episodes of a few hours of intense con-vection. The evolution of the morphology of the convective cyclone after the convective pulse stopped shows a strong relation between the convective energy released and the initial vorticity in the cyclone. Similar results are obtained for the cyclonic storm observed during the Voyager 2 flyby. We also compare our simulations of these storms with numerical simulations of a storm that developed in the STB in 2018 inside an elongated cyclone known as the South Temperate Belt Ghost [Inurrigarro et al., Observations and numerical modelling of a

La atmósfera de Júpiter es muy rica en estructuras dinámicas dignas de estudio y sus características bandas conforman un amplio espectro de velocidades zonales en diferentes sentidos. En la latitud de 23,5º N se encuentra el más intenso de los jets jovianos, alcanzando velocidades de hasta 150 m/s. Es en esta misma banda, denominada Banda Templada Norte (North Temperate Belt, NTB), donde ocasionalmente se genera una serie de particulares perturbaciones, denominadas NTB disturbances (NTBD). Un nuevo estudio sobre este tipo de perturbaciones se presenta en este trabajo. La perturbación en cuestión corresponde con tres tormentas convectivas que surgieron durante el año 2020 en Júpiter en la banda NTB. La presencia de estas perturbaciones de escala planetaria abarcó desde mediados de agosto hasta mediados de octubre, lo que supone unos dos meses de vida. El objetivo principal del trabajo consiste en el estudio de la velocidad de las estructuras que se forman con el movimiento de la perturbación a partir de imágenes tomadas con telescopios terrestres y su posterior modelizado como ondas de Rossby, de manera que se pueden caracterizar tanto su estructura como sus condiciones de propagación. En el trabajo que se presenta se corroboran los resultados de estudios previos sobre la perturbación de 2016, que se compararán a lo largo del proyecto, y se añade el estudio sobre la perturbación de NTBD como onda de Rossby, planteado en dichos estudios., Jupiterren atmosfera, ikertzeko interesgarriak diren egitura dinamikoetan aberatsa da eta haren banda bereizgarriek norantza desberdinetako abiadura zonalen espektro zabala osatzen dute. 23,5°N latitudean intentsitate handieneko jet jobianoa aurkitzen da, 150 ms−1ko abiadurara iristen delarik. Banda zehatz honi Iparraldeko Banda Epela (North Temperate Belt, NTB) deritzo, eta bertan perturbazio berezi batzuk sortzen dira noizean behin, NTB disturbances (NTBD) izenekoak. Mota honetako perturbazioen inguruko azterketa berri bat aurkezten da lan honetan. Aztertuko den perturbazioa 2020. urtean zehar Jupiterren NTB bandan sortu ziren hiru ekaitz konbektiboei dagokie. Eskala planetarioko perturbazio horien presentziak abuztuaren erdialdetik urriaren erdialdera iraun zuen, bi hilabete inguruko bizitza suposatzen duena. Lan honen helburu nagusia lurreko teleskopioen bidez lortutako irudietan oinarrituz perturbazioaren mugimenduaren ondorioz sortutako egituren abiaduraren ikerketan eta haien ondorengo Rossby uhinen bidezko modelizazioan datza, modu horretan haien egitura zein propagazio baldintzak ezaugarritu daitezkelarik. Aurkeztutako lanean 2016. urteko perturbazioarekin lotutako aurretiko ikerketetan lortutako emaitzak berresten dira, proiektuan zehar alderatuko direnak, eta aurreko ikerke- tetan proposatutako azterketa bat gehitzen da: NTBD perturbazioa Rossby uhin moduan ikertzea., Jupiter’s atmosphere is very rich in worth studying dinamic structures and its characte- ristic bands form a wide range of zonal velocities in different directions. The most intense Jovian atmospheric jet is located at 23,5°N latitude, reaching eastwards velocities up to 150 ms-1. Is in this very band, called North Temperate Belt (NTB), where several disturbances appear from time to time. These events are known as NTB disturbances. A new study on this type of perturbances is presented in this project. This phenomenon is formed by three convective storms that appeared in 2020 at NTB band in Jupiter.The presence of these planetary scale disturbances spanned from August to October, which means a two months duration. The main aim of the project lies in studying the velocity of the structures formed due to the perturbation motion by analysing images obtained with terrestrial telescopes and, later, apply the Rossby waves model in order to characterise both structure and conditions of propagation. In this project, previous results of 2016 NTB disturbance studies are con rmed and compared, adding a new interpretation, proposed on those studies, based on Rossby waves.

Español: Este proyecto está centrado en el estudio de las tormentas de polvo en la atmósfera del planeta Marte. Se ha escogido como caso de análisis el inicio de la Gran Tormenta de Polvo del año 2018 (GDS 2018) y de la tormenta precursora a este evento. Se ha llevado a cabo un estudio amplio en torno a la climatología de Marte y el desarrollo de tormentas de polvo en el planeta. Asimismo se ha realizado un análisis de la evolución temporal, las texturas y el papel de la convección seca como mecanismo de inyección de polvo en el onset de la tormenta de polvo global de 2018 y la tormenta precursora. Para conseguir esto, se han ejecutado simulaciones numéricas a partir del uso de bases de datos y se han navegado las imágenes tomadas por el instrumento MARCI durante el evento, obteniendo resultados que se han puesto en contexto gracias a la consulta de investigaciones en el campo., Euskera: Proiektu hau Marte planetaren atmosferako hauts ekaitzen ikerketan zentratuta dago. Azterketa-kasu gisa, 2018ko Polvoko Tormenta Handiaren (GDS 2018) eta ekitaldi horren aurreko ekaitzaren hasiera aukeratu da. Ikerketa zabala egin da Marteko klimatologiaren eta planetako hauts-ekaitzen garapenaren inguruan. Era berean, konbekzio lehorrak 2018ko hauts-ekaitz globalaren eta aurreko ekaitzaren onsetean hautsa injektatzeko mekanismo gisa duen zeregina, ehundurak eta denbora-bilakaera aztertu dira. Hori lortzeko, zenbakizko simulazioak egin dira datu-baseen erabileran oinarrituta, eta MARCI instrumentuak ekitaldian zehar hartutako irudiak nabigatu dira. Emaitza horiek testuinguruan jarri dira, eremuko ikerketen kontsultari esker.

Nine simulations are used to predict the meteorology and aeolian activity of the Mars 2020 landing site region. Predicted seasonal variations of pressure and surface and atmospheric temperature generally agree. Minimum and maximum pressure is predicted at Ls similar to 145 degrees and 250 degrees, respectively. Maximum and minimum surface and atmospheric temperature are predicted at Ls similar to 180 degrees and 270 degrees, respectively; i.e., are warmest at northern fall equinox not summer solstice. Daily pressure cycles vary more between simulations, possibly due to differences in atmospheric dust distributions. Jezero crater sits inside and close to the NW rim of the huge Isidis basin, whose daytime upslope (similar to east-southeasterly) and nighttime downslope (similar to northwesterly) winds are predicted to dominate except around summer solstice, when the global circulation produces more southerly wind directions. Wind predictions vary hugely, with annual maximum speeds varying from 11 to 19 ms(-1) and daily mean wind speeds peaking in the first half of summer for most simulations but in the second half of the year for two. Most simulations predict net annual sand transport toward the WNW, which is generally consistent with aeolian observations, and peak sand fluxes in the first half of summer, with the weakest fluxes around winter solstice due to opposition between the global circulation and daytime upslope winds. However, one simulation predicts transport toward the NW, while another predicts fluxes peaking later and transport toward the WSW. Vortex activity is predicted to peak in summer and dip around winter solstice, and to be greater than at InSight and much greater than in Gale crater.

We report a previously unnoticed annually repeating phenomenon consisting of the daily formation of an extremely elongated cloud extending as far as 1,800 km westward from Arsia Mons. It takes place in the solar longitude (Ls) range of ∼220°–320°, around the Southern solstice. We study this Arsia Mons Elongated Cloud (AMEC) using images from different orbiters, including ESA Mars Express, NASA MAVEN, Viking 2, MRO, and ISRO Mars Orbiter Mission (MOM). We study the AMEC in detail in Martian year (MY) 34 in terms of local time and Ls and find that it exhibits a very rapid daily cycle: the cloud growth starts before sunrise on the western slope of the volcano, followed by a westward expansion that lasts 2.5 h with a velocity of around 170 m/s in the mesosphere (∼45 km over the areoid). The cloud formation then ceases, detaches from its formation point, and continues moving westward until it evaporates before the afternoon, when most sun-synchronous orbiters make observations. Moreover, we comparatively study observations from different years (i.e., MYs 29–34) in search of interannual variations and find that in MY33 the cloud exhibits lower activity, while in MY34 the beginning of its formation was delayed compared with other years, most likely due to the Global Dust Storm. This phenomenon takes place in a season known for the general lack of clouds on Mars. In this paper we focus on observations, and a theoretical interpretation will be the subject of a separate paper.

[ES] En este trabajo hemos estudiado unos fenómenos meteorológicos presentes en la atmósfera de Marte conocidos como tormentas de polvo con textura. Hemos caracterizado estas tormentas mediante el análisis de algunas imágenes obtenidas por el instrumento MARCI a bordo de MRO, y hemos realizado un análisis teórico para explorar el papel de la convección en la formación de las estructuras observadas en las mismas.

We present the first systematic study of clouds observed during twilight on Mars. We analyze images obtained by the Visual Monitoring Camera (VMC) on Mars Express between 2007 and 2020. Using an automated retrieval algorithm we found 407 cases of clouds observed at twilight, in which the geometry of the observations allows to derive the minimum altitude, revealing that many of these clouds are in the mesosphere (above 40km and up to 90km). The majority of these mesospheric clouds were detected in mid-latitudes at local autumn and winter, a new trend only hinted at by previous studies. In particular, we find a massive concentration of clouds in the southern mid-latitudes between Terra Cimmeria and Aonia, a region where high altitude events have been previously observed. We propose that there is an unknown mechanism in these regions that enhances the probability to host high altitude clouds around the southern winter solstice.

In June 2015, Cassini high-resolution images of Saturn's limb southwards of the planet's hexagonal wave revealed a system of at least six stacked haze layers above the upper cloud deck. Here, we characterize those haze layers and discuss their nature. Vertical thickness of layers ranged from 7 to 18km, and they extended in altitude 130km, from pressure level 0.5bar to 0.01bar. Above them, a thin but extended aerosol layer reached altitude 340km (0.4mbar). Radiative transfer modeling of spectral reflectivity shows that haze properties are consistent with particles of diameter 0.07-1.4mum and number density 100-500cm-3. The nature of the hazes is compatible with their formation by condensation of hydrocarbon ices, including acetylene and benzene at higher altitudes. Their vertical distribution could be due to upward propagating gravity waves generated by dynamical forcing by the hexagon and its associated eastward jet.

The Mars Express mission of the European Space Agency (ESA) has been in the orbit of Mars since 2003 and has made great contributions to improve the existent knowledge about the red planet. Two of the instruments of this spacecraft are the Visual Monitoring Camera (VMC) and the High Resolution Stereo Camera (HRSC). The main objective of this project has been to study the different dynamical features (hazes, clouds, dust arcs, dust storms) that can be seen in the north polar region of the planet during the spring season (Ls= 0⁰-90⁰) of the northern hemisphere in the 35th MY (Martian Year). In addition to taking measurements of these structures, a theoretical analysis of the obtained results has been done using tools like the Mars Climate Database (MCD)., La misión Mars Express de la Agencia Espacial Europea (ESA) lleva en la órbita de Marte desde el año 2003 y ha contribuido a aumentar el conocimiento existente sobre el planeta rojo. Dos de los instrumentos de esta nave son la Visual Monitoring Camera (VMC) y la High Resolution Stereo Camera (HRSC). El objetivo de este trabajo ha sido el de usar imágenes de esos instrumentos para estudiar las distintas estructuras (neblinas, nubes, arcos de polvo y tormentas de polvo) que se forman en la región polar norte del planeta durante la primavera (Ls= 0⁰-90⁰) de dicho hemisferio en el año marciano 35. Además de medir estas estructuras se ha realizado un análisis teórico de los resultados obtenidos empleando herramientas como el Mars Climate Database (MCD)., Europako Espazio Agentziaren (ESA) Mars Express misioa 2003tik dago Marteren orbitan eta planeta gorriari buruz dagoen ezagutza handitzera lagundu du. Espazio ontzi honetako bi instrumentu Visual Monitoring Camera (VMC) eta High Resolution Stereo Camera (HRSC) dira. Proiektu honen helburua tresna horien irudiak erabiltzea izan da, marteko 35. urteko hemisferio horren udaberrian (Ls= 0⁰-90⁰) planetaren iparraldeko eskualde polarrean sortzen diren estrukturak (lainoak, hodeiak, hauts-arkuak eta hauts-ekaitzak) aztertzeko. Egitura horiek neurtzeaz gain, lortutako emaitzen analisi teorikoa egin da, Mars Climate Database (MCD) bezalako tresnak erabiliz.

167 p., Planetary atmospheres other than that of Earth provide natural laboratories to test our theories and models for climate studies and can help to identify the physical processes involved in the behaviour and evolution of a planet's climate. Mars has always played a predominant role in comparative studies with Earth. Extensive efforts placed in the robotic exploration of Mars have retrieved large amount of data its atmosphere. Dust aerosol is the main driver of Mars' atmospheric variability, and the determination of the particles' properties is of high relevance for estimating its climate forcing. In particular, the angular distribution of sky brightness can be evaluated to retrieve valuable information regarding the physical properties of the aerosol particles. In this study we show that images retrieved by the Mars Science Laboratory (MSL) engineering cameras (Navcam and Hazcam) can be used to constrain the size and shape of dust aerosol particles, and to derive the column dust optical depth. A radiative transfer based iterative retrieval method was implemented in order to determine the aerosol modelling parameters that best reproduce the sky radiance as a function of the scattering angle observed by MSL engineering cameras. Results show an overall good agreement with previous studies and have contributed to extend the available data and to parameterise dust phase functions. The tools and procedures developed during this research can be implemented for the analysis of retrievals from future Mars exploration missions.

We study the 2018 Martian global dust storm (GDS 2018) over the Southern Polar Region using images obtained by the Visual Monitoring Camera (VMC) on board Mars Express (MEx) during June and July 2018. Dust penetrated into the polar cap region but never covered the cap completely, and its spatial distribution was nonhomogeneous and rapidly changing. However, we detected long but narrow aerosol curved arcs with a length of ~2,000–3,000 km traversing part of the cap and crossing the terminator into the nightside. Tracking discrete dust clouds allowed measurements of their motions that were toward the terminator with velocities up to 100 m/s. The images of the dust projected into the Martian limb show maximum altitudes of ~70 km but with large spatial and temporal variations. We discuss these results in the context of the predictions of a numerical model for dust storm scenario.

We analyze the onset and initial expansion of the 2018 Martian Global Dust Storm (GDS 2018) using ground-based images in the visual range. This is the first case of a confirmed GDS initiating in the Northern Hemisphere. A dusty area extending about 1.4×105 km2 and centered at latitude +31.7°±1.8° and west longitude 18°±5°W in Acidalia Planitia was captured on 30 and 31 May 2018 (Ls = 184.9°). From 1 to 8 June, daily image series showed the storm expanding southward along the Acidalia corridor with velocities of 5 m/s and simultaneously progressing eastward and westward with horizontal velocities ranging from 5 to 40 m/s. By 8 June the dust reached latitude -55° and later penetrated in the South polar region, whereas in the North the dust progression stopped at latitude approximately +46°. We compare the onset and expansion stage of this GDS with the previous confirmed storms.

183 p., En esta tesis se aborda el estudio de la atmósfera de Marte al nivel de la superficie con datos provenientes de la estación meteorológica REMS, uno de los instrumentos del rover de NASA Curiosity situado en el interior del cráter Gale en una latitud ecuatorial. Estos datos se han complementado con observaciones orbitales obtenidas por el instrumento MARCI en el orbitador MRO. Los datos observacionales se han interpretado a partir de la comparación con los resultados de modelos de circulación general almacenados en forma de base de datos climática en la denominada MCD.El periodo estudiado en esta tesis va desde el 6 de agosto de 2012, fecha del aterrizaje de la misión MSL, hasta el 8 de noviembre de 2016, lo que corresponde a más de dos años marcianos. Estos datos permiten estudiar las variaciones meteorológicas diarias, estacionales, el paso de tormentas de polvo, efectos locales asociados a la interacción de la atmósfera con la topografía y eventos transitorios rápidos como el paso de vórtices convectivos capaces de levantar columnas de polvo de la superficie.Los estudios realizados en esta tesis tendrán su continuación natural en un futuro inmediato con la llegada nuevas misiones espaciales equipadas con estaciones meteorológicas como son: Insight con su aterrizaje previsto a finales de 2018 y su estación meteorológica Twins, y Mars 2020 y su estación meteorológica MEDA. De este modo y en un horizonte muy cercano será posible el estudio de la meteorología marciana con una red discreta de estaciones meteorológicas y observaciones orbitales. Así, el trabajo presentado en esta tesis puede considerarse como preparatorio para una nueva era de datos sobre la atmósfera de Marte que permitirá dar respuesta a algunas de las preguntas que se plantearán como resultado de esta investigación.

200 p., PlanetCam-UPV/EHU es una cámara astronómica `lucky imaging¿ diseñada para la obtención de imágenes de alta resolución de objetos del Sistema Solar, principalmente como apoyo a la investigación científica en dinámica atmosférica y estudios de estructura vertical de nubes en las atmósferas planetarias. El instrumento trabaja simultáneamente en dos canales, cada uno con su propio detector y filtros del interés en el rango Visible (0.38 - 1 ¿m) e infrarrojo cercano SWIR (1 - 1.7 ¿m). El instrumento contiene varios filtros seleccionados para imágenes de color y una amplia serie de filtros correspondientes a las bandas de absorción de metano y CO2, así como sus longitudes de onda adyacentes, todos ellos seleccionados por su interés en los estudios planetarios. El objetivo principal dentro del alcance de esta tesis ha sido caracterizar el funcionamiento radiométrico y astronómico de PlanetCam, así como su calibración en reflectividad absoluta, proporcionando valores de la reflectividad absoluta de Júpiter y de Saturno a lo largo de cuatro años de observación. Por otra parte, se ha realizado una serie de estudios científicos de los principales planetas del Sistema Solar en términos de dinámica atmosférica así como un modelo de transferencia radiativa para el análisis de la estructura vertical de la atmósfera de Júpiter.

132 p., En esta tesis, estudiamos la dinámica de las regiones polares de Saturno a nivel de las nubes de amoniaco desde 60º a 90º latitud mediante el análisis de imágenes multiespectrales de muy alta resolución capturadas por las cámaras del instrumento Imaging Science System (ISS) de la nave Cassini entre Octubre 2006 y Septiembre 2014 en longitudes de onda del visible entre el ultravioleta (~ 400 nm) y el infrarrojo cercano (~ 1000 nm) y nos centramos en la comparación de la dinámica entre ambas regiones polares. Con el fin de estudiar la dinámica de estas regiones, medimos el movimiento horizontal de las nubes y construimos mapas de viento zonal y meridional, junto con perfiles de viento zonal medio, desde 60º hasta el polo. Por otro lado, construimos mapas de vorticidad relativa y mapas bisimensionales de vorticidad potencial tanto de Ertel como quasi-geostrófica. Además, con el propósito de entender la naturaleza de la dinámica observada en ambas regiones polares, caracterizamos la morfología nubosa de la región polar norte de Saturno a diferentes longitudes de onda y analizamos su variación temporal. Finalmente, estudiamos varias posibles interpretaciones de la naturaleza del Hexágono, utilizando los vientos obtenidos al inicio de la tesis. Los resultados de este estudio nos muestran que la dinámica en ambas regiones polares es muy similar, alcanzando valores tanto de velocidades zonales como de vorticidades muy similares en ambos casos. Por otro lado vemos que, a pesar de observar variaciones en la apariencia del vórtice polar norte y actividad de tipo convectiva en el Hexágono, ninguna de estas estructuras muestra cambios estacionales en su dinámica.

The zonal wind profile of Saturn has a unique structure at 60°N with a double-peaked jet that reaches maximum zonal velocities close to 100 ms−1. In this region, a singular group of vortices consisting of a cyclone surrounded by two anticyclones was active since 2012 until the time of this report. Our observation demonstrates that vortices in Saturn can be long-lived. The three-vortex system drifts at u = 69.0 ± 1.6 ms−1, similar to the speed of the local wind. Local motions reveal that the relative vorticity of the vortices comprising the system is ∼2–3 times the ambient zonal vorticity. In May 2015, a disturbance developed at the location of the triple vortex system, and expanded eastwards covering in two months a third of the latitudinal circle, but leaving the vortices essentially unchanged. At the time of the onset of the disturbance, a fourth vortex was present at 55°N, south of the three vortices and the evolution of the disturbance proved to be linked to the motion of this vortex. Measurements of local motions of the disturbed region show that cloud features moved essentially at the local wind speeds, suggesting that the disturbance consisted of passively advecting clouds generated by the interaction of the triple vortex system with the fourth vortex to the south. Nonlinear simulations are able to reproduce the stability and longevity of the triple vortex system under low vertical wind shear and high static stability in the upper troposphere of Saturn.

We present a study of the cloud morphology and motions in the north polar region of Saturn, from latitude ∼ 70°N to the pole based on Cassini ISS images obtained between January 2009 and November 2014. This region shows a variety of dynamical structures: the permanent hexagon wave and its intense eastward jet, a large field of permanent “puffy” clouds with scales from 10 – 500 km, probably of convective origin, local cyclone and anticyclones vortices with sizes of ∼1,000 km embedded in this field, and finally the intense cyclonic polar vortex. We report changes in the albedo of the clouds that delineate rings of circulation around the polar vortex and the presence of “plume-like” activity in the hexagon jet, in both cases not accompanied with significant variations in the corresponding jets. No meridional migration is observed in the clouds forming and merging in the field of puffy clouds, suggesting that their mergers do not contribute to the maintenance of the polar vortex. Finally, we analyze the dominant growing modes for barotropic and baroclinic instabilities in the hexagon jet, showing that a mode 6 barotropic instability is dominant at the latitude of the hexagon.

Saturn has an intense and broad eastward equatorial jet with a complex three-dimensional structure mixed with time variability. The equatorial region experiences strong seasonal insolation variations enhanced by ring shadowing, and three of the six known giant planetary-scale storms have developed in it. These factors make Saturn's equator a natural laboratory to test models of jets in giant planets. Here we report on a bright equatorial atmospheric feature imaged in 2015 that moved steadily at a high speed of 450 ms(-1) not measured since 1980-1981 with other equatorial clouds moving within an ample range of velocities. Radiative transfer models show that these motions occur at three altitude levels within the upper haze and clouds. We find that the peak of the jet ( latitudes 10 degrees N to 10 degrees S) suffers intense vertical shears reaching + 2.5 ms(-1) km(1), two orders of magnitude higher than meridional shears, and temporal variability above 1 bar altitude level. Palabras clave

134 p., Esta tesis constituye un estudio de la dinámica atmosférica observada en las nubes del planeta Venus con datos procedentes de dos misiones espaciales separadas en el tiempo: la misión Galileo y la misión Venus Express, ésta última actualmente en curso. En particular, se han utilizado imágenes obtenidas en diferentes longitudes de onda para estudiar los movimientos de las nubes en varios niveles verticales de la atmósfera, lo que permite trazar la dinámica atmosférica global del planeta. En esta tesis se presentan por primera vez medidas simultáneas de la estructura de vientos del planeta en tres dimensiones (zonal, meridional y vertical al utilizar diferentes nubes separadas en altura) encontrándose y analizando diferentes fuentes de variabilidad temporal que incluyen mareas térmicas producidas por la insolación solar, oscilaciones globales del viento y variabilidad entre periodos de tiempo de varios meses a años. También se ha realizado un estudio de las escalas características de estas nubes y de la turbulencia atmosférica que gobierna en parte la estructura de diferentes escalas observadas en las nubes de Venus. En las imágenes de mayor resolución del instrumento VIRTIS en Venus Express se aprecian frecuentemente estructuras periódicas en las nubes inferiores y que se corresponden a un tipo de ondas atmosféricas conocidas como ondas de gravedad cuyas características y papel en la dinámica atmosférica se analizan al final de la tesis.